1. Field of the Invention
The present invention relates to a process for formulating p-phenylenediamine color developing agents into granular form, these developing agents being used as a color developing agent for natural-color photography (or color photography).
2. Description of the Prior Art
P-Phenylenediamine color developing agents are known in the art, and may be used either in their free form or in their salt form. For example, some of the compounds are described in U.S. Pat. No. 2,193,015 (1940) and 2,108,243 (1938); British Pat. No. 778,437 (1957); J. Am. Chem. Soc., Vol. 73, pp 3100 - 3125 (1951), etc. More specifically, 4-amino-3-methyl-N-ethyl-N-[(beta-methanesulfonamido)-ethyl]aniline sesquisulfate monohydrate, 4-amino-N,N-diethylaniline monosulfate monohydrate, 4-amino-N-ethyl-N-(beta-hydroxyethyl)aniline monosulfate, 4-amino-N-ethylaniline monosulfate, 4-amino-3-methyl-N-ethyl-N-(beta-hydroxyethyl)aniline monosulfate, 4-amino-N-ethyl-N-(beta-methylsulfonamidoethyl)aniline monosulfate, and the like are examples of these developing agents.
These p-phenylenediamine color developing agents (hereinafter referred to as merely "color developing agent") have heretofore been marketed as fine powders. However, they are so light that they tend to scatter and, in addition, they will cause medicinal dermatitis (poisoning) on the parts of a body contacting them due to their toxicity (mainly dermatitis problems). In addition, some of these color developing agents become difficult to handle due to the solidification during storage even though, when they were produced, they were powders tending to scatter.
This tendency to solidify is increased by a slight amount of ambient moisture, and the smaller the size of the powders, the more easily the powders solidify in a short time due to their larger contact area.
In addition, since such powders are high in adhesive properties to each other, the powders flow poorly. Although powders from which this slight amount of water has been completely removed show good fluidity for a short time, this property will disappear within several hours in extreme cases. Therefore, the packaging process therefor requires a great deal of time.